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August 15, 2008

A Climate Connection in the Clouds

UMBC Physics Professor Co-Authors Science Paper on How Aerosols Impact Cloud Formation, Climate

Media Contact:
Chip Rose, UMBC Science/Tech News
410-455-5793
crose@umbc.edu

Researchers at UMBC, NASA-Goddard Space Flight Center and the Weizmann Institute in Rehovot, Israel studying the connection between the burning of vegetation and cloud cover in the Amazon region have found a clearer picture of how aerosols – the tiny particles that make up dust, soot, smoke and ocean spray – may impact cloud formation and climate change on a global scale. The study was published today in the journal Science.

Scientists have long known that aerosols play a role in cloud formation, but were puzzled by the fact that aerosols’ impact was inconsistent, causing more cloud cover over the Atlantic Ocean while causing less in South America’s Amazon basin.

Aerosol particles are carried by the wind into the atmosphere, where they become encased by water to form rain droplets that cluster into clouds. Aerosol-rich clouds are more spread out by wind, last longer and produce less rain. Aerosol-rich clouds also trap heat in the atmosphere, making cloud growth and rain less likely.

The research team focused on the Amazon region as a test area, using NASA’s Terra satellite to study cloud and aerosol data. “During the (2005) dry season in the Amazon, the only aerosols of any magnitude are from smoke emerging from human-initiated fires,” said study co-author Lorraine Remer, a physical scientist at NASA’s Goddard Space Flight Center, in a NASA press release.

The end result of the research was an analytical model that should work across the globe.

“As we’d expected in applying our model, increased smoke from the fires created clouds rife with a more pronounced radiative effect -- rich with human-caused aerosols that absorbed sunlight, warmed the local atmosphere, and blocked evaporation. This led to reduced cloud cover over the Amazon,” study co-author Vanderlei Martins, associate professor of physics at UMBC, said in the NASA press release. “And it’s encouraging to know the science behind our model should stand no matter the region.”

The paper, “Smoke Invigoration Versus Inhibition of Clouds over the Amazon,” can be found in the Aug. 15 issue of Science.

A Science podcast featuring the Amazon aerosol research is available at:

http://www.sciencemag.org/cgi/content/full/321/5891/981b


Posted by crose at August 15, 2008 10:47 AM